We look at the effects of aromatherapy in 3 types of clinical care. After smelling an essential oil, a woman with cognitive decline who had become withdrawn was livelier and began to talk more. A girl with extreme sensitivity to sound happily took off her earmuffs. A terminal cancer patient with fluid in his abdomen and pain felt better, regained his appetite and began to sleep well. We look at the latest findings in the field of chemical ecology and brain science to find out why aromas have such effects.